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authorTony Luck <tony.luck@intel.com>2009-10-12 09:51:41 -0700
committerTony Luck <tony.luck@intel.com>2009-10-13 14:28:31 -0700
commit1502f08edc040b6ba4b986454416564088995e79 (patch)
treec6bc0d0c01d9bbc5503b86db71ca977d1b89e0f1 /arch/ia64/include
parent9d40ee200a527ce08ab8c793ba8ae3e242edbb0e (diff)
[IA64] SMT friendly version of spin_unlock_wait()
We can be kinder to SMT systems in spin_unlock_wait. Signed-off-by: Tony Luck <tony.luck@intel.com>
Diffstat (limited to 'arch/ia64/include')
-rw-r--r--arch/ia64/include/asm/spinlock.h17
1 files changed, 15 insertions, 2 deletions
diff --git a/arch/ia64/include/asm/spinlock.h b/arch/ia64/include/asm/spinlock.h
index 4fa502739d6..239ecdc9516 100644
--- a/arch/ia64/include/asm/spinlock.h
+++ b/arch/ia64/include/asm/spinlock.h
@@ -75,6 +75,20 @@ static __always_inline void __ticket_spin_unlock(raw_spinlock_t *lock)
ACCESS_ONCE(*p) = (tmp + 2) & ~1;
}
+static __always_inline void __ticket_spin_unlock_wait(raw_spinlock_t *lock)
+{
+ int *p = (int *)&lock->lock, ticket;
+
+ ia64_invala();
+
+ for (;;) {
+ asm volatile ("ld4.c.nc %0=[%1]" : "=r"(ticket) : "r"(p) : "memory");
+ if (!(((ticket >> TICKET_SHIFT) ^ ticket) & TICKET_MASK))
+ return;
+ cpu_relax();
+ }
+}
+
static inline int __ticket_spin_is_locked(raw_spinlock_t *lock)
{
long tmp = ACCESS_ONCE(lock->lock);
@@ -123,8 +137,7 @@ static __always_inline void __raw_spin_lock_flags(raw_spinlock_t *lock,
static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)
{
- while (__raw_spin_is_locked(lock))
- cpu_relax();
+ __ticket_spin_unlock_wait(lock);
}
#define __raw_read_can_lock(rw) (*(volatile int *)(rw) >= 0)